before you remove the wheel, you might turn the wheel from lock to lock and count the number of rotations. Then divide that number in 2 . Turn the wheel from one side ( say all the way to the left) to the right , the exact number you got when did the dividing. Now your steering gear is centered. If the steering wheel is not straight, you'll need to remove and center it or you might check to see if the steering shaft is installed 90 degress off at either the steering gear end or the firewall end. ( if it's possible to be off on your truck)
Then you'll have the wheel centered in relation to the steering gear. When you drive the truck you'll see if the steering gear is centered with relationship to the front end alignment. You might need to adjust the front end to bring things to straight. You can do this by adjusting the drag link that goes from the steering gear to the wheel. ( do not adjust the tie rod that goes from one wheel to the other or you'll mess up the alignment) When you're all done, you might consider a front end alignment.
good luck